Immunological agglutination reactions are currently used for identifying various kinds of blood types as well as for detecting various kinds of antibodies and antigens in blood samples and other aqueous solutions. In such procedures, a sample of red blood cells is mixed with serum or plasma in a consumable device such as a test tubes, microplates or in the method knows in the art as column agglutination technology (CAT), a card or cassette tube configuration, wherein the mixture is incubated and then centrifuged. Various reactions then occur or do not occur depending on, for example, the blood types of the red blood cells or whether certain antibodies are present within the blood sample. These reactions manifest themselves as clumps of cells or as particles with antigens or antibodies on their surfaces, referred to as agglutinates. The failure of any agglutinates to appear indicates no reaction has occurred, while the presence of agglutinates, depending on the size and amount of the clumps formed, indicates the presence of a reaction and the level of concentration of cells or antibodies in the sample and reaction strength.
As described, for example, in U.S. Pat. No. 5,512,432 to LaPierre et al., an agglutination test method has been developed and successfully commercialized, which method employs gel or glass bead microparticles contained within a small column, referred to as a microcolumn or a microtube. The said microcolumn or microtube is arranged as one of a plurality of columns formed in a transparent card or cassette format wherein multiple such tubes containing reagents are molded into a single consumable. A reagent, such as anti-A, is dispensed in a diluent in the microcolumns of the card or cassette and test red blood cells are placed in the reaction chamber above the column. The column, as part of the entire card or cassette, is then centrifuged. The centrifugation accelerates the reaction, if any, between the red blood cells and the reagent, and also urges any cells toward the bottom of the column. In the meantime, the glass beads or the gel material acts as a filter, and resists or impedes downward movement of the particles in the column. As a result, the nature and distribution of the particles in the microcolumn provides a visual indication of whether any agglutination reaction has occurred, and if such a reaction has occurred, the strength of the reaction based on the relative position of the agglutinates in the column. If no agglutination reaction has occurred, then all or virtually all of the red blood cells in the microtube will pass downward during the centrifugation procedure, to the bottom of the column in the form of a pellet. Conversely and if there is a strong reaction between the reagent and the red blood cells, then virtually all of the red blood cells will agglutinate, and large groupings will form at the top of the microtube above the gel or bead matrix in that the matrix is sized not to let these clumps pass through. Reactions falling between these latter two extremes are possible in which some but not all of the red blood cells will have agglutinated. The percentage of red blood cells that agglutinate and the size of the agglutinated particles each have a relationship with the strength of the reaction. Following the centrifugation process and after all processing steps have been completed, the microtube is visually examined by either a human operator or by machine vision such as a CCD camera for imaging the resulting reaction between the red blood cells and the reagent which is then classified. The reaction is classified as being either positive or negative, and if positive, the reaction is further classified into one of four classes depending on the strength of the reaction.
Currently, clinical immunohematology utilizes so-called gel cards and/or glass bead cassettes which are known consumable test elements and employ a plurality of microtubes for purposes of creating agglutination reactions as described above for blood grouping, blood typing, antigen or antibody detection and other related applications and uses. Thus, multiple types of test elements are known for the various blood grouping, typing and antigen antibody tests. These consumable test elements commonly include a planar substrate that supports a plurality of transparent columns or microtubes, each of the columns containing a quantity of an inert material, such as the aforementioned gel material or glass beads, respectively, that is coated with an antigen or antibody or material or is provided with a carrier-bound antibody or antigen, each of the foregoing being provided by the manufacturer. A pierceable wrap completes the assembly of the test element. This wrap which may be for example in the form of an adhesively or otherwise—attached foil wrap, covers the top side of the test element to cover the contents of each column. This same foil wrap conveniently provides a reflective surface which is utilized in the method of the instant invention as detailed hereinbelow. Once the covering wrap is pierced, aliquots of patient sample and possibly reagents (e.g., if reagents are not first added by the manufacturer or additional reagents, depending on the test) can be added to the columns, either manually or using automated apparatus. The test element thus containing patient sample (e.g., red blood cells and sera) is then incubated and following incubation, the test element is spun down by centrifugation, as noted above, in order to accelerate an agglutination reaction that can be graded either based on the position of agglutinates within each transparent column of the test element or cassette or due to a lack of agglutination based on the cells settling at the bottom of the test column. As shown in FIGS. 1 & 2, also present on the test element 20, 30 is typically located a barcode 55 bearing information identifying the reagents for the immunohematologic test type for that test element. Other barcode information on the test element can include shelf expiration, lot number, and the sequence of that test element within a given manufacturer's lot, among any other indicating information as desired by the manufacturer.
A number of automated or semi-automated apparatus, such as those manufactured by Ortho-Clinical Diagnostics, Inc., DiaMed A.G., Bio-Rad, and Grifols, are known that utilize a plurality of test elements in the form of gel cards or bead cassettes, such as those manufactured and sold by Micro-Typing Systems, Inc., DiaMed A.G., and BioRad, among others. Currently, test elements for a single immunological assay type are obtained from the manufacturer arranged in containers such as boxes or sleeves having multiple such cards or cassettes in separate slots. These boxes or sleeves conveniently fit in lanes of a slide tray in a drawer which is part of the analyzer. Depending on analyzer type, size and capacity, the slide tray in the drawer of an analyzer may accommodate from five (5) to twelve (12) such lanes separated by rails, permitting from five (5) to twelve (12) sleeves to be accommodated in an analyzer. Each container (sleeve) may contain for example twenty (20) cards or cassettes. This physical space limitation for sleeves and sleeve capacity restricts the types of immunological test element types to a maximum of twelve (12), one type per sleeve. However, there are currently about fifteen (15) to twenty (20) different test element (cards or cassettes) types available for use in blood analysis testing, for example including various manufacture-available ABO blood-type and blood antibody-type test element cards/cassette types. Thus the requirement for operator intervention to insert and exchange specific cards upon physician order is high. The operator or technician using the apparatus must therefore load the appropriate sleeve containing the desired cards or cassettes, which requires opening the card/cassette loading area (CCLA) of the apparatus and manually inserting into a slot within the sleeve the one or more desired cards or cassettes for the appropriate immunological test(s). Such manual interaction by the operator with the analyzer requiring opening the analyzer drawer to access the sleeves and changing the test element necessarily interrupts the blood testing process and delays results.
As described, each of the consumable test elements includes a top side adhesive wrap. This wrap conveniently comprises a foil wrap which covers the microcolumns and forms a seal relative to the contents of the microcolumns further preventing microcolumn contents from drying out or degrading. To allow for inventory control, analyzers made by the above-mentioned companies are equipped with software permitting detection functionality to determine which consumable or test element (card or cassette) positions are in fact loaded with a consumable test element and of which type. In one aspect of the invention, an optical proximity sensor detects the reflective difference between the presence and absence of the foil wrapped consumable test element. An algorithm in the sub-processor of the apparatus thus determines the inventory for the consumable test element of a given type.
Following optical sensing of all sleeves within the clinical analyzer apparatus, and when all slots in a sleeve contain the same type test element, inventory of particular test element types is quickly performed by a gripper in the analyzer picking a single consumable test element from each sleeve and reading with a barcode reader or camera system of the type that will be familiar to one having skill in the relevant art, to determine the type of test element loaded in the entire sleeve. However, such methodology does not permit more than one type of test element per sleeve. Since picking every consumable test element in the sleeve to determine the consumable type would make inventory function too slow for practical use, the instant invention is directed to a method and container to provide a flexible inventory determination of multiple types of test elements in a single sleeve. This avoids the need to swap out sleeves to introduce test elements of different types.